ZipKit Touch Demo won't run on device

I'm running the latest snapshot release from the site and get a SIGABRT at the following line in ZKCDTrailer.m:

bq. line 53

commentLength = [self.comment zk_precomposedUTF8Length];

The same code will run in the simulator though.

I'm running iPhone OS 3.0 and 3.1.

Thanks.